1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a toner for developing an electrostatic image, and more particularly, to a toner for developing an electrostatic image, which can enhance all of a wide fusing latitude, a gloss, anti-cohesiveness, storage stability, and low-temperature fixing ability.
2. Description of the Related Art
Toners for developing an electrostatic image are used in printing devices based on electrophotographic and electrostatic image developing processes.
From among quality items of toners, a small particle size, narrow particle size distribution, wide color gamut, and low fixing temperature have become important. The small particle size, the narrow particle size distribution, and the wide color gamut are required to obtain a print image of high quality, and the low fixing temperature is required to reduce energy consumption required to print and carbon dioxide emissions. In addition, other quality items such as heat storage ability, anti-cohesiveness of toners, and charging stability have become important.
As a toner producing method, a pulverizing process is known. However, in the pulverizing process, excessive energy is consumed to produce a toner of a small particle size, and it is difficult to control morphology of a toner particle. In addition, a releasing agent or a pigment is exposed to the surface of a toner particle, and thus there is a problem that the anti-cohesiveness and storage ability of the toner easily deteriorate.
An emulsion and aggregation (EA) process is known as another method for producing toners. In the EA process, a toner particle is grown through aggregation of particles of various raw materials. Accordingly, the quality items such as the small particle size and the narrow particle size distribution can be easily achieved in the EA. In addition, it is relatively easy to control the morphology of the toner particle, high resolution can be obtained by enhancing dot/line reproducibility, and energy saving, enhanced transfer efficiency, and charging stability can be achieved by reduction in an amount of toner.
The EA process has been on the spotlight due to the above-described advantages. A toner which is produced in the EA process is called a “polymerized toner.” In the related-art EA process, a styrene-acrylate copolymer is used as a binder resin. However, in various application fields of color toners, there is still a demand for enhancement of transparency and fixing temperature of the binder resin.
The related-art method suggests a toner particle which has a resin layer (shell) formed on the surface of a coloring particle (core particle) containing a resin and a coloring agent, in order to provide a polymerized toner which does not cause a change in image concentration, which is caused by a change in a charging property and a developing property, fogging, and a change of a color image even when an amount of coloring agent existing on the particle surface is small and the toner is provided to form an image for a long time under a high-humidity environment. This method can enhance charging uniformity between colors by suppressing surface exposure of the coloring agent.
However, when much wax which is a releasing agent is contained, for example, the heat storage ability and the anti-cohesiveness of toners may deteriorate due to plasticization which is caused by partial miscibility between a low molecular weight portion and a binder resin of the wax.
In addition, a method for reducing glass transition temperature (Tg) of the binder resin and capsulating the binder resin to have somewhat high Tg has been suggested to fix at low temperature. However, it is known that this method can achieve the aim of fixing at low temperature, but is not enough to achieve heat storage ability and a high gloss.